It is a common practice to place security-sensitive computers and other apparatus which emits electromagnetic radiation (EMR), or which is receptive to electromagnetic interference (EMI), inside a shielded cabinet. When such a cabinet is intended to remain closed, the task of sealing the cabinet against EMI or EMR is not a very demanding one.
The conventional non-openable cabinets typically have used compression-type gaskets to seal the joints between the various components of the cabinet. It is also known, in the case of a cabinet which has a removable panel of the occasional-access type, to provide the panel with a flange in the form of a forwardly directed blade, and to provide the panel opening with a seal strip which has bendy fingers.
These bendy fingers press laterally against the sides of the flange. The flange engages the fingers with a wiping action as the panel is assembled into the opening. This type of seal is very effective and reliable.
Such an arrangement of a blade-like flange and a wiper seal requires a straight line motion of the panel into the opening. The required straight line motion, furthermore, has a considerable length of travel, typically 2 cm or so of movement of the panel between the position in which the blade or flange is fully closed into the seal strips and the position in which the blade is quite clear of the seal strips.
The arrangement of a blade-like flange and a wiper seal may be applied to a removable panel, as described, where providing the 2 cm of straight line travel is not difficult. The arrangement may also, in some cases, be applied to the hinged door of a room.
In the case of a hinged door for a room, it is generally a simple matter to position the hinge axis in such a place that a near-enough approximation to the required 2 cm or so of straight line travel of the door can be achieved.
For a hinged door, a line drawn, in the plan view, from the hinge axis to the nearest point of the line of engagement between the seal strip and the flange, should be at least 10 cm or so long. Also, this line should lie in, or near, the plane of the door frame.
When these conditions are met, the arcuate travel of the door about the hinge axis has such a small lateral component, at least over the 2 cm of door-closing movement, that the flange moves, relative to the seal strip, in what amounts to a straight line, perpendicular to the door frame.
Thus the blade-like-flange-and-wiper-seal arrangement, with its requirement for straight-line, or almost straight-line, travel of the flange into the seal strip, may be used where the door hinge axis is positioned 10 cm or so away from the seal.
It is recognised that such positioning of the hinge can be achieved relatively easily in the case of the door of a room, but in the case of a door for a shielded cabinet, inevitably the hinge axis has to be much closer to the edge of the door, i.e. to the seal, than 10 cm.
It is an aim of the invention to provide a means by which the blade-like-flange-and-wiper-seal arrangement, even though that arrangement has a requirement for 2 cm or so of straight-line, or almost straight-line, travel of the flange into the seal strip, can be utilised for an openable, hinged door of a shielded cabinet.